title: cis-clerodane diterpene lactones from Amphiachyris dracunculoides.
abstract: Four cis-ent-neoclerodane lactones, amphiacrolide A [2], amphiacrolide B [3], amphiacrolide C [4] and amphiacrolide D [5] were isolated from the aerial parts of Amphiachyris dracunculoides, and their structures established by physical and chemical methods. High field 1H- and 13C-nmr assignments were made for each compound and some of their derivatives by using one- and two-dimensional nmr techniques including nOe difference, COSY, and CH-correlation of one-bond and multiple bond (COLOC) relationships. A chemical correlation of the amphiacrolides to gutierolide [1], a compound with absolute stereochemistry determined by X-ray analysis, established the stereochemistry for the group. Consequently, a compound having reported properties identical with amphiacrolide D [5] must have its structure revised to contain the beta-faced epoxide. Amphiacrolide A [2] had not been reported previously.
authors.affiliation: Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, Ohio State University, Columbus 43210.
authors.forename: F M
authors.initials: FM
authors.lastname: Harraz
authors.forename: R W
authors.initials: RW
authors.lastname: Doskotch
mesh_terms: D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification*; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010946:Plants, Medicinal / Q000032:analysis*
chemical_list: D004224:Diterpenes; D007783:Lactones